Randolph diagram

2013-12-30T20:51:25Z

174.44.201.118: /* Application to set theory */ Loose use of isomorphism, nonsense term "logic theory" for logic, formal logic

{{enzyme
| Name = EPSP Synthase (3-phosphoshikimate 1-carboxyvinyltransferase)
| EC_number = 2.5.1.19
| CAS_number = 9068-73-9
| IUBMB_EC_number = 2/5/1/19
| GO_code = 0003866
| image = EPSP synthase.PNG
| width =
| caption = EPSP synthase liganded with shikimate.<ref name="pmid16225867">{{cite journal | author = Priestman MA, Healy ML, Funke T, Becker A, Schönbrunn E | title = Molecular basis for the glyphosate-insensitivity of the reaction of 5-enolpyruvylshikimate 3-phosphate synthase with shikimate | journal = FEBS Lett. | volume = 579 | issue = 25 | pages = 5773–80 |date=October 2005 | pmid = 16225867 | doi = 10.1016/j.febslet.2005.09.066 }}</ref>
}}
{{Pfam_box
| Symbol = EPSP_synthase
| Name = EPSP synthase (3-phosphoshikimate 1-carboxyvinyltransferase)
| image = EPSP synthase cartoon.PNG
| width =
| caption = Ribbon diagram of EPSP synthase
| Pfam= PF00275
| InterPro= IPR001986
| SMART=
| Prosite = PDOC00097
| SCOP = 1eps
| TCDB =
| OPM family=
| OPM protein=
| PDB=
}}

'''5-enolpyruvylshikimate-3-phosphate (EPSP) synthase''' is an [[enzyme]] that [[catalysis|catalyzes]] the [[chemical reaction]]:

:phosphoenolpyruvate + 3-phosphoshikimate <math>\rightleftharpoons</math> phosphate + 5-enolpyruvylshikimate-3-phosphate (EPSP)

Thus, the two [[enzyme substrate (biology)|substrates]] of this enzyme are [[phosphoenolpyruvic acid|phosphoenolpyruvate]] and 3-phospho-[[shikimic acid|shikimate]], whereas its two [[product (chemistry)|products]] are [[phosphate]] and 5-enolpyruvylshikimate-3-phosphate.

== Nomenclature ==

The enzyme belongs to the family of [[transferase]]s, to be specific those transferring aryl or alkyl groups other than methyl groups. The systematic name of this enzyme class is '''phosphoenolpyruvate:3-phosphoshikimate 5-O-(1-carboxyvinyl)-transferase'''. Other names in common use include:
{{div col|colwidth=25em}}
* 5-enolpyruvylshikimate-3-phosphate synthase,
* 3-enolpyruvylshikimate 5-phosphate synthase,
* 3-enolpyruvylshikimic acid-5-phosphate synthetase,
* 5'-enolpyruvylshikimate-3-phosphate synthase,
* 5-enolpyruvyl-3-phosphoshikimate synthase,
* 5-enolpyruvylshikimate-3-phosphate synthetase,
* 5-enolpyruvylshikimate-3-phosphoric acid synthase,
* enolpyruvylshikimate phosphate synthase, and
* 3-phosphoshikimate 1-carboxyvinyl transferase.
{{Div col end}}

== Function ==

The enzyme participates in biosynthesis of the [[aromatic]] amino acids [[phenylalanine]], [[tyrosine]] and [[tryptophan]]. The enzyme is a target for [[herbicides]] as these amino acids are only synthesized in plants and microorganisms. [[Glyphosate]] acts as a [[enzyme inhibitor|competitive inhibitor]] for phosphoenolpyruvate and is used as a broad-spectrum [[:wikt:systemic|systemic]] herbicide.<ref name="pmid11171958">{{cite journal | author = Schönbrunn E, Eschenburg S, Shuttleworth WA, Schloss JV, Amrhein N, Evans JN, Kabsch W | title = Interaction of the herbicide glyphosate with its target enzyme 5-enolpyruvylshikimate 3-phosphate synthase in atomic detail | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 98 | issue = 4 | pages = 1376–80 |date=February 2001 | pmid = 11171958 | pmc = 29264 | doi = 10.1073/pnas.98.4.1376 }}</ref><ref name="pmid21668647">{{cite journal | author = Pollegioni L, Schonbrunn E, Siehl D | title = Molecular basis of glyphosate resistance-different approaches through protein engineering | journal = FEBS J. | volume = 278 | issue = 16 | pages = 2753–66 |date=August 2011 | pmid = 21668647 | doi = 10.1111/j.1742-4658.2011.08214.x }}</ref>

== Shikimate pathway ==

The [[shikimic acid|shikimate pathway]] is a seven step metabolic route used by bacteria, fungi, and plants for the biosythesis of [[aromatic amino acids]] ([[phenylalanine]], [[tyrosine]], and [[tryptophan]]). The fourth aromatic amino acid [[tyrosine]] can be synthesized from phenylalanine. This pathway is not found in animals, hence the products of this pathway represent [[essential amino acid]]s that must be obtained from the animal's diet.

== Structure ==

EPSP synthase is a monomeric enzyme. It is composed of two domains, which are joined by protein strands. This strand acts as a hinge, and can bring the two protein domains closer together. When a substrate binds to the enzyme, ligand bonding causes the two parts of the enzyme to clamp down around the substrate in the active site.

== Reaction ==

EPSP synthase catalyzes the reaction which converts shikimate-3-phosphate plus phosphoenolpyruvate to 5-enolpyruvylshikimate-3-phosphate (EPSP).

[[File:EPSPreactionII.tif|600px]]{{clear-left}}

==Applications==

=== Herbicides ===

[[Glyphosate]] is a chemical herbicide which kills plants by inhbiting the shikimate pathway. It targets EPSP synthase, the enzyme that catalyzes the conversion of shikimate-3-phosphate and phosphoenolpyruvate into EPSP. Glyphosate is a [[competitive inhibition|competitive inhibitor]] of the enzyme. Glyphosate resembles the [[transition state]] that transforms the reactants into products in the reaction that is catalyzed by EPSP synthase. Hence glyphosate (as a [[transition state analog]]) binds more tightly to EPSP synthase than its natural substrate and thereby prevents binding of substrate to the enzyme.<ref name = "pmid11171958"/>

This binding leads to the inhibition of the enzyme, and consequently shuts down the entire pathway. Since plants require the shikimate pathway to produce aromatic amino acids, this kills the plant. This also means that glyphosate is generally harmless to animals and humans, since they are not dependent on the shikimate pathway for the synthesis of Phe, Trp, and Tyr and instead obtain these amino acids from their diet.

==References==
{{reflist}}

==Further reading==
{{refbegin}}
* {{cite journal | author = Morell H, Clark MJ, Knowles PF, Sprinson DB | year = 1967 | title = The enzymic synthesis of chorismic and prephenic acids from 3-enolpyruvylshikimic acid 5-phosphate | journal = J. Biol. Chem. | volume = 242 | pages = 82–90 | pmid = 4289188 | issue = 1 | url=http://www.jbc.org/content/242/1/82.long }}
{{refend}}

[[Category:EC 2.5.1]]
[[Category:Enzymes of known structure]]

Fraction of inspired oxygen

2012-06-26T00:19:04Z

174.44.187.112: /* PaO2/FiO2 ratio */ < or = 200 suggests ARDS not greater than 200 as was stated previously

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Randolph diagram

Fraction of inspired oxygen